This research will contribute to the auditory data being amassed on def patients who have received an implanted cochlear prosthesis at the House Ear Institute in Los Angeles. Specifically, this is a psychophysical study concerned with assessing their auditory ability to perceive a brief interruption, or gap, in the electrical signal they are being stimulted with. The gap-detection paradigm that will be used in this research is also designed to provide a measure of the time course of decay in the auditory sensation that persists from stimulation. In the field of auditory-implant psychophysics, this project is also unique in that it will provide data on the range of auditory performance in a relatively large group of implant patients who have all had experience using the same type of auditory prosthesis. The findings from this study will be a valuable addition to the baseline auditory data needed to aid in the development of a more effective auditory data needed to aid in the development of a more effective auditory prosthesis for the profoundly deaf.